Jurassic The Hunted

During the level U-1229 you'll have to find travel though some caves to get to a Sub. Right before you get to the Sub you'll get teleported into a smaller cave where a lot of little dinos. These guys take one hit melee to kill and don't cause much damage. You'll kill about 20 of these guys in this cave alone. Maybe a little less. If it doesn't unlock just melee a few red raptors in other levels after shooting them once.